Having trouble foiling on new PM style build

Hello Builders, I’ve constructed a Pacificmeister style e-foil but after a few attempts in the water, I can’t quite make it fly. According to my GPS, I peaked at 8 or 10mph which I think should be enough to get me up on the wing. I’ve never ridden a foil before so I’m not sure if it’s new rider ignorance or a problem with my setup.

I am riding on calm, flat water with no waves and I don’t really feel like the wing is trying to lift me. If I stand on the back of the board, the front tilts up and the motor drives toward the surface. I can bring the nose out of the water but the tail drags. If I stand on the front, the whole board stays stuck in the water. I have tried the rear wing in both positions on the lower mast.

In any case, I would appreciate some advice. I am totally new to foiling so don’t assume I’ve gotten the “obvious” stuff right. Thank you!

Liquid Force Rocket Foil, chosen for low minimum foil speed
Rider: 77kg (170 lbs)
SSS 360kV motor
5:1 PLE 40 gearbox
12S battery (approx 48V nominal)
400A Flier Boat ESC - intentional overkill to ward off overheating
3 blade Pacificmeister prop - draws 75A at full throttle and therefore seems well matched to motors and gearbox
Board - Modified and fiberglassed a SUP blank - approx 200L for buoyancy

Reasonably accurate CAD model (minus a few screws):
[Onshape](http://OnShape E-Foil CAD Model)


Post some pictures of the board all put together. The board, mast, motor, and foil. That will help us determine if something is out of wack.


What limits have you applied to the ESC?

I run a similar Setup with a SSS56104 420KV, 5:1 gear and FR high pitch 135mm prop.
Foil is RL 800x170mm with 1200cm2 surface. Plenty of power, speed to get on the foil is around 15km/h and on the foil I reached 30km/h but never went to full throttle. So even with a 360KV you should reach enough speed to foil. What max RPM do you reach without load? Could also be drag from the duct, maybe try without duct.

You probably don’t have enough speed. The rocket foil is an old foil and its design isn’t great. It doesn’t have a low minimum foil speed compared to larger wingsets. My advice would be to put more weight forward until you feel that the board is starting to plane. From there slowly shift your weight on your back foot and the board should lift off (keep the throttle where it is). I suggest you do ups and downs first to get used to the foiling feeling. To do that you will have to shift your weight between your front door which will bring the board down and your back foot which will bring the board up!

I have the same motor and gearbox. With 12s I have about 3200 RPM at nominal voltage (3.7v), with a flier 320A ESC.
Previously I had a liquid force wind as per PM and now a Gong pro M. In both cases plenty of power to fly, also with duct. My old LF seems rather similar as yours.

From what I read you tried several riding positions. Did it start to plane on the water? One thing to avoid is to try to fly to early, let the board get some speed, let it plane and then with this speed lean back and the board should come lose from the water. 200L is quite a board though.

75A when plowing through the water seems actually a bit on the low side to me. What kind of battery do you have and how much A can it provide?

If it already planes, but lacks last bit of speed, you could opt for a higher pitch prop. This setup has a lot of torque and if the 75amp is all it draws at close to take of speed than I guess you can up it here a bit. Once you fly the amp draw should reduce quite a bit

Thanks for the speedy responses everyone. I’ll take “as built” pictures and post them as soon as I get off work tonight. The CAD model is pretty accurate overall.

75A does seem low for ploughing so I’ll check that my Ammeter is reading correctly. I have 4x Turnigy 12AH 6S 12C LIPO packs 2 packs in series, 2 in parallel to reduce the current through each. 12AH16C2Batteries= 384A from the total battery pack. I don’t think I have applied any limits on the Flier 400A Boat ESC but I will double check and report back. I’ll measure no-load RPM, too. I guess I can figure that out from the electrical frequency as I do not have a shaft sensor.

I know 200L is a large board volume but about half of it floats out of the water at rest with me standing on it. I wanted to have ample floatation even when stopped because I am a beginner. I kept it to 30" wide, which seems comparable to the drag cross section professional builds. I fall off pretty often and am uncomfortable without the prop guard in place. - Maybe I could do a quick test without them as an absolute last resort. For anyone running a Rocket Foil, what was your minimum foiling speed?

How do I decide if the board is planing vs ploughing on flat bottomed hull?

I have been trying to perform the exercises in these lift foils and fliteboard videos but I never lift out of the water:

When you feel it more like gliding/bumping over the water. You really feel that difference in how the board behaves, it is faster and more stable too.
Guess the batteries should deliver the punch.
I also don’t think you can limit the flier in this way. Did you adjust the timing of your ESC?
Als have a look how much amp you draw free spinning. I had about 3.5 a 4 amp

How thick is the profile of your duct? If you feel uncomfortable you could still print a much thinner profile but add a layer of fibre glass to reinforce it. I did that and made a big difference.

Ok, I got the electrical measurements. I tested the ammeter against a known current and it is working correctly. I improvised a shaft sensor from a magnet and coil of wire.

No load current: 6A - higher than expected but ok for now
No load RPM: approx 3600 RPM.

Reassembling things now, pictures to follow shortly.

I like the idea of reinforcing the duct with fiberglass. I’ll have to get supplies for that. How thin did you dare to go?
Right now I am using the PM Duct_rev3. Using calipers, it measures 7.5mm thick at it’s widest point.

The board is definitely more stable when it’s moving but I feel like it might still be ploughing. The nose pitches up and the back digs in which doesn’t seem like proper planing to me. How far up the mast do you normally mount the pod? Maybe the low propeller pod is causing the front to pitch up and back to pitch down.

Is it common to have to shim the wing angle to generate lift?

I’ll be happy to post any other cad files or pictures for diagnosis.

Full Assembly


Motor Pod Detail:

Mast and MotorDetail:

Went down to 6mm max thickness of the printed part. I also added 3.2 mm holes to the struts and reinforced them with 3mm carbon rods. The duct is stable and works well, could not test the max speed of the system yet: Daniels (un)geared inflatable (slowly built) - #19 by sat_be - Builds - FOIL.zone


Looking at your pictures the mast is a bit far forward. Try mounting the mast as far back as you have holes for. Also, the design of the rails on the nose of the board is not ideal. The sharp edges will plow. You might have to fix that to get the board to not plow under everytime it touches the water surface.

I have not used that specific foil but it looks pretty small. So, you’re gonna need to go pretty fast to get it to foil. I’d guess +15mph.

The motor mounted as low on the mast as possible is correct. That looks good.

It will take you some practice to learn then feel and technique.

When you start out the board is traveling slow and the motor is providing a strong pitch up force. Try to give just enough throttle to slowly pick-up speed. As you give throttle keep shifting your weight forward. The best learning position is on your knees. Scoot as far forward as you can. You will feel like you’re hanging off the nose of the board. Lean forward and push down on the nose with your hand if needed.

Once you get enough speed that the wing is flying (probably 15 mph on that small wing) then you will feel the pitch of the board start to pitch down. As this happens you need to start shifting your weight back and reduce throttle a bit.

I suggest getting a bigger wing for learning. Something around 2,000 CM surface area. The infinity 84 is what I teach people on.


1 Like

If the nose is pulling up it’s because you are lying too far back on the board. So many guys do this when they first start foiling or surfing.
As you gain speed the foil will bring the nose up if you are too far back. If you get your weight further forward you keep the nose low and the board can get on the plane.
The further forward you are the easier it is when you start to stand as the foil stays down. Then just press down on the back foot and you’ll be up in no time.
I taught someone that had never surfed or foiled in 10 minutes last weekend… With the correct technique it’s super easy…

Hey Gang! I bought a Slingshot Infinity 84 wing and I popped right out of the water! Thanks for the advice. Now to learn how to ride this thing…

1 Like